[Tig] More memories please

[Tom Tcimpidis]

Hi Ed,

I first became familiar with the PE-15 at college when I helped build the
Educational TV station there.  
Most everything that we used was donated, including the cameras.  The only
things we actually bought were a used GE TT-6
Tetrode UHF transmitter that was broadbanded for color, a colorized VR1200
(our only Intersync machine), and a Scala slot UHF antenna.  Our master
control switcher
was particularly interesting in that it was a GE binary relay switcher.
Each buss (there were four) had two sets of relays that fed in to a vertical
interval 2x1 swtich for that bus.  When you took a source, it would first
close the relay for the selected source on the selected bus and then
performed the4 vertical interval switch to that buss.  When you next took a
different source on that buss, it would reverse the process.  It actually
worked surprisingly well.

The four PE-15s that we received were something of a basket case and I spent
weeks making them in to decent cameras. They came sans IOs, color separation
filters, knee ND filters, and in various states of disrepair.  Since the
factory color filters were long ago no longer available, I spent time with
different combinations of gel separation filters coming up with the right
combinations to produce the desired results.  I also elected to use a
different method of gamma and knee than was recommended by GE in "The
Manual."   GE suggested that ND filters be selected to produce the same IO
knee in each channel, which was standard technique for IO color cameras.
However, they also suggested that the tubes be run just below the knee point
and that the gamma circuit in the CCU be used for camera correction. I
decided early on that, while this produced better sensitivity, it also
produced a very noisy image.   So, I selected ND filters to produce a
slightly higher knee in green than in red and blue. This allowed me to use
the innate knee of the IO for most of my gamma correction in Red and Blue
and to trim it with just a bit of electronic gamma in those two channels.
This produced a quieter image and a more stable camera. 

I had more than one occasion to see images from various TK-41s at the time
and I believe that our PE-15's held up very well in comparison. They
produced an image with pleasing colorimetry (similar to that of a PC-70).
Good signal to noise and resolution (they had transistor preamps which was a
little unusual for the time), and surprisingly good registration.  They also
proved to be fairly reliable over the years I was there.  

We also had three Marconi MkIII black and white cameras with 4 1/2" IOs and
they produced some of the nicest looking black and white pictures I have
ever seen.  It was also interesting that they were able to do almost
everything in that camera with the same tube - the 6DJ8.

Tom



Hi Tom,

Enjoyed your memories of the G.E. Image Orthicon color camera.

I am putting together a page on my color television history site
about the GE camera which came out about 1958.

Where was your experience with the camera?  Can you name any
other stations that had the GE camera?  How good was its
colorimetry as compared to a TK-41?

I plan to reproduce several color pages from a brochure on the
camera.  Liked the idea that the camera taking optical horizontal
axis was higher and closer vertically to the axis of the
viewfinder (too many TK-41 shots required the cameraman to be on
a step stool).  But have never heard how good was its color.

Ed